Humidifier with reduced aerosolization of pathogens and dissolved solids found in source water

ABSTRACT

The present invention relates to the field of room humidifier devices, and more particularly to an ultrasonic humidifier that reduces or eliminates aerosolization of pathogens and dissolved solids found in source water.

This patent application claims the benefit of U.S. Provisional Application Ser. No. 63/296,043, filed on Jan. 3, 2022, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of room humidifier devices, and more particularly to an ultrasonic humidifier providing for REDUCED aerosolization of pathogens and dissolved solids found in source water.

DISCUSSION OF RELATED ART

There is a growing body of evidence on the health benefits of maintaining proper indoor humidity. For example, recent studies have shown that increasing indoor humidity from 20% to 40% can decrease influenza infection rates by 80%. A humidifier is an electrical appliance designed to increase humidity in a single room or an entire building. It is estimated that 15% of American homes have a humidifier.

Ultrasonic humidifiers are believed to be the most prevalent type of humidifier, at least for the consumer market, as they tend to be the most efficient and have the lowest cost compared to the alternatives. Such humidifier devices typically use a ceramic piezoelectric diaphragm vibrating at an ultrasonic frequency to create water droplets that exit the humidifier in the form of cool fog with little or no perceived noise, which is desirable.

However, there is a significant problem with these types of humidifiers. Studies show such ultrasonic humidifiers aerosolize 90% of the impurities found in the device's water reservoir. The impurities include inorganic minerals and dissolved solids (TDS) found in the source water (and in all tap water) as well as any organic pathogens such as bacteria that can grow in the stagnant charge water while it is contained in the device's water reservoir. Most consumers are unaware their humidifier will increase the airborne particle count by 20× in a matter of minutes. As a result, ultrasonic humidifiers must be cleaned regularly. Consumers would need to use distilled water as the source water to prevent airborne pathogens and avoid a sticky white dust being spread throughout the air, and the resulting airborne dispersion of impurities in the water. Unfortunately, distilled water is not as readily available to the consumer as tap water, and most consumers use tap water as the source water.

The impurity-inhalation and other potential risks associated with ultrasonic humidifiers have been investigated by many researchers in the past. The risks are associated with fine particulate matter generated from the humidifier operation. These studies determined the mass concentration, chemical composition, morphology, size distribution and the total numbers of particulate matter generated by an ultrasonic humidifier, and scientifically established that particulate matter emitted from humidifiers is composed of inorganic compounds having a composition directly mirroring that in the charge water. These studies concluded that the size and mass concentration of particulate matter both increase with the amount of solute in the charge water.

Some manufacturers have added UV light sources/filters to remove organic pathogens. Such UV treatment has no effect upon the inorganic solids (TDS). Some manufacturers have implemented a cleaning mode in which detergents/cleaning solutions such as citric acid are used to clean the water tubing to reduce accumulations of the organic pathogens. Such cleaning solutions have no effect upon the problems associated with the inorganic solids/TDS, and sometimes they result in water contamination.

As an alternative to ultrasonic humidifiers, evaporative humidifiers do not aerosolize the dissolved solids. However, such evaporative humidifiers pose other problems. For example, such evaporative humidifiers use wicks that become moldy and can become saturated with mineral deposits over time. Further, they are less efficient than ultrasonic humidifiers and are unable to regulate their humidification rate.

As another alternative to ultrasonic humidifiers, vaporizers or steam humidifiers are less likely to aerosolize impurities in the water. However, they use a substantial amount of energy compared with ultrasonic humidifiers and they pose far greater health safety risks, including fire and burn risks.

There is a need or desire for a humidifier that can provide for safe operation using impurity-laden tap water, which reduces or prevents aerosolization of inorganic minerals and dissolved solids found in source tap water, and airborne pathogens, and avoids harmful impacts to humans resulting from the inhalation of such airborne particles.

SUMMARY

The present invention provides a humidifier that provides for safe operation by reducing or preventing aerosolization of inorganic minerals and dissolved solids found in source water, and airborne pathogens, and avoids harmful impacts to humans resulting from the inhalation of such airborne particles.

BRIEF DESCRIPTION OF THE FIGURES

An understanding of the following description will be facilitated by reference to the attached drawings, in which:

FIG. 1 is a front view of an exemplary humidifier device in accordance with an exemplary embodiment of the present invention;

FIG. 2 is a side view of an exemplary humidifier device of FIG. 1 ;

FIGS. 3 and 3B are front views of an exemplary humidifier device of FIG. 1 with FIG. 3 showing a front cover open for illustrative clarity; and FIG. 3 b showing the front cover closed;

FIG. 4 is a rear perspective view of the water reservoir of the exemplary humidifier device of FIG. 1 ;

FIGS. 5 and 6 are perspective views of components of the water reservoir of FIG. 4 ;

FIGS. 7 and 8 are front and side views, respectively, of the water reservoir of FIG. 4 ;

FIGS. 9A and 9B are top and rear perspective views of the humidifier device of FIG. 1 ;

FIG. 10 is an exploded top perspective view of the humidifier device of FIG. 1 ;

FIG. 11 is a top view of the humidifier device of FIG. 1 ;

FIG. 12 is a schematic illustrating the components of the exemplary humidifier device of FIG. 1 ;

FIG. 13 is a graph illustrating the relationship between relative humidity and air quality index for water containing dissolved solids;

FIG. 14 is a flow diagram illustrating an exemplary method of operation of an exemplary control system of the exemplary humidifier device of FIG. 1 for power management; and

FIG. 15 is a schematic illustrating an exemplary method of operation of an exemplary control system of the exemplary humidifier device of FIG. 1 during normal humidification operation.

DETAILED DESCRIPTION

Operation of known room air humidifier appliances can increase room air humidity, but they often introduce airborne contaminants into the room air, which is undesirable and can be harmful to one's health if inhaled. The contaminants include bacteria and other pathogens that may be found in the source water, such as tap water, and/or that may grow within the water reservoir or elsewhere within the device. In the case of ultrasonic humidifiers, the airborne contaminants may include minerals and/or other materials present as dissolved solids in the source water. Unfortunately, distilled water is not as readily available to the consumer as tap water and most consumers do not use distilled water, but instead use tap water as the source water, which provides such contaminants. The present invention provides a humidifier device that provides for safe operation by reducing or preventing aerosolization of inorganic minerals and dissolved solids found in source water and airborne pathogens, and thereby avoids harmful impacts to humans resulting from the inhalation of such airborne particles.

FIGS. 1-12 shown an exemplary room air humidifier device 100 providing for reduced aerosolization of pathogens and dissolved solids found in source water in accordance with an exemplary embodiment the present invention. As shown in FIG. 1-12 , the exemplary humidifier device 100 includes a housing 10 enclosing and/or supporting a number of components, including a water purification system and a humidification system. The housing 10 can be cylindrical as shown or can have another suitable shape. The housing 10 can be made of plastic such as polyethylene, polypropylene, or polycarbonate, or can be made of another suitable material. Referring now to FIGS. 3 and 12 , it will be appreciated that a cover 12 of the housing 10 may be opened and/or removed to access internal components of the humidifier 100. As discussed below, the humidifier 100 can principally include a water tank 20, a water filter 40, an ultraviolet-C (UV-C) light source 50, a pump 60, a motorized fan 70, an air filter 80, and a humidification chamber 90, which can be arranged as shown.

Many conventional ultrasonic humidifiers position an upper water tank above a lower reservoir containing a water-atomizing piezoelectric disc or other humidification structures, rely upon gravity to move water into the reservoir, and provide for substantial water accumulation and length of passage of water vapor through the humidifier 100 that can promote undesirable bacterial growth. By contrast, the exemplary embodiment of the present invention positions the water tank 20 below an upper humidification chamber 90 that is at or near an exit point of the humidifier 100. This reduces water accumulation and length of passage of water vapor through the humidifier 100, and thus reduces or eliminates opportunities for bacterial growth. Instead, the water from tank 20 is first filtered by filter 40. The filtered water is then pressurized by a pump 60 and pumped to the upper humidification chamber 90 at or adjacent an exit point of the humidifier 100, near the fan 70 and upper end of the housing 10, as will be appreciated from FIGS. 3 and 12 .

The humidifier 100 includes a water filter 40 configured to filter debris and/or dissolved solids, such as minerals, from charge water contained in the water tank 20. The water filter 40 can be positioned upstream from the UVC filter 50, the pump 60 and the humidification chamber 80, so that atomized water has already been filtered and cleaned before reaching the humidification chamber 90. This avoids the release and dispersion of dissolved solids into the room air.

The humidifier 100 may include the UVC filter 50, which can be a UV-C light source (which may include a broad-band light source and/or a UV-C filter), positioned to expose charge water from the water tank 20 and upstream from the humidification chamber 90 to a dose of UV-C radiation. The dose of UV-C radiation can be operable (in combination with flow rate, etc.) to kill pathogens contained in the charge water that would otherwise be dispersed into room air. As shown in FIG. 12 , the UV-C filter 50 can be positioned along tubing 46 and 56 connecting the water filter 40 to the pump 60.

In accordance with the present invention, tubing connecting each individual component and the individual components themselves are coated or impregnated with antimicrobial or hydrophobic additives to further avoid pathogen growth within the humidifier 100. This is particularly applicable to tubes 46 and 56 between the water filter 40 and pump 60, and tube 66 between the pump 60 and humidifier chamber 90. Such coatings can also be applied to inlet tube 30 which draws water from the water tank 20 to the water filter 40, and overflow tube 98 that carries overflow water from the humidifier chamber 90 back to the water tank 20.

In accordance with the present invention, the housing 10 may include a cover 14 which can be cylindrical as shown in FIG. 3 . The cover 14 can be provided with openings 12 in a region surrounding the air filter 80. The openings 12 can be positioned to pass air into and through air filter 80. The motorized fan 70 is operable to draw inlet air (ambient room air) into the housing 10 via the openings 12 and through the filter 80, which can be a HEPA filter comprising HEPA filtration media, and then exhaust the filtered air from the housing 10 along with atomized water entrained in the exhausted air through the humidification chamber 90 and into the surrounding room atmosphere. In this manner, the humidifier 100 atomizes water and exhausts it into the room using air that has been filtered and is free (or substantially free) of dissolved solid contaminants captured by the water filter 40 and pathogens eliminated by exposure to the UV light source 50. Accordingly, the humidifier 100 provides for safe operation even when using impurity-laden tap water by reducing or preventing aerosolization of inorganic minerals and dissolved solids found in source water and airborne pathogens, and avoids harmful impacts to humans resulting from the inhalation of such airborne particles.

Referring now to FIGS. 3-8 , the water tank 20 is shown in greater detail. The water tank 20 includes a reservoir 22 for holding and storing charge water. Preferably, the reservoir can be constructed of transparent material to allow the user to visually assess the water quality and level within the reservoir 22. The internal surface of the water tank may be provided with an antimicrobial coating and/or embedded additive.

The exemplary water tank 20 can include a lid 24 configured to form a close fit with a top of the reservoir 22. The lid 24 can include an outlet port 26 and an inlet port 28. The outlet port 26 is connected to inlet tube 30 for drawing water from a bottom of the reservoir 22, and the output port 26 provides a fitting 27 for connecting tube 46 for passing water drawn from the reservoir 22 to the pump 60. In this embodiment, the water filter 40 can be removably attached to a lid housing 42 (FIGS. 5 and 6 ) such that the combination collectively forms the lid 24 (FIG. 4 ). The water filter 40 may be removed and replaced with a fresh water filter 40 after the original filter's filtration capacity has been diminished through use, as will be appreciated from FIGS. 4-6 . The inlet tube 30, water filter 40 and outlet port 26 collectively define a passage for drawing water from the reservoir 22 through the water filter 40. The inlet tube 30 may include reverse osmosis filtration media.

The water filter 40 can be constructed to provide an elongated (e.g., maze-like) route of passage through filtration media of the water filter 40 to optimize filtration capacity and/or effectiveness. In one embodiment, the water filter 40 can be made of inorganic material with ion extraction properties. By way of example, the water filter 40 may employ resin beads, a reverse osmosis filter and/or activated carbon as filtration media materials.

More specifically, the filtration media of water filter 40 can be made of technological materials like resin that are able to capture and retain inorganic compounds from the water flow. Usually, the goal is to maximize the trajectory length of a given water volume element through the filter, such that contact time with the absorbing material is extended. Therefore, the water filter 40 may be constructed to increase the water flow hydrostatic resistance due to restricting the effective flow area. The resistance may be elevated during the initial priming of the water through the filter or when the filter gets clogged with minerals from the water. In certain embodiments, the device may include a control system 99 providing pump control logic that accounts for water filter resistance, as discussed below with reference to FIG. 14 . The water filter 40 can be connected to the water tank 20 on a separate loop or can be connected in the main water path. In certain embodiments, a sensor may be provided in the humidification chamber 90 to assess the total dissolved solid (TDS) concentration in the water. The TDS sensor measures the water electrical conductivity and calculates the concentration estimate based on its calibration characteristic, since there is a strong correlation between conductivity of water and concentration of dissolved mineral ions.

As will be appreciated from FIGS. 3 and 12 , tubing 46 attaches to the fitting 27 of the outlet port 26 and passes water along the UV light source 50 for killing pathogens entrained in the charge water. In the exemplary embodiment, the UV light source 50 is positioned upstream from the pump 60, as best shown in FIG. 12 . In the exemplary device showing, the tubing 46 can extend along the upper portion 18 of housing 10 (FIG. 3 ), which can enclose the UV light source 50, pump 60, motorized fan 70 and humidification chamber 90, with the air filter 80 disposed between the upper housing 18 and lid 24 of the water tank 20.

The UV light source 50 may be an in-line or an external application of UV light from UV-capable bulbs or LEDs, preferably UV-C light, that provides light capable of breaking down the DNA, RNA and/or proteins of organic pathogens such as bacteria, fungi, virus, and animal and plant cells and thus “kills” these pathogens. The light source 50 may include one or more external LEDs in parallel that illuminate a transmissible section of the LED and may have reflective surfaces. The degree of germicidal effectiveness is related to the dose rate on the incident surface. The dose is a product of intensity and exposure time in seconds.

${{Dose}{Rate}} = {\frac{mJ}{{cm}^{2}} = {\frac{mw}{{cm}^{2}}*\sec}}$

The dose rate and distance between the UV light source and a central streamline of the tubing are two key factors that determine the effectiveness of sterilization. By way of example, the UV irradiation intensity can be reduced up to 80% at a distance of 10 cm from the light source. Effectiveness is also impacted by the length of the UV light source segment as well as by the water flow rate. UV LEDs may draw several watts of electricity, and appropriate heat sinking measures may be taken to dissipate the outside the device.

The UV light source 50 may be positioned adjacent fused silica or quartz tubing, and UVC light emitting diodes and enclosure may be provided to limit UV light leakage. The UV light source 50 can be connected to a respective power electronics and controlled by a centralized microcontroller of the control system 99 (FIG. 14 ).

The pump 60 may be a peristaltic constant displacement pump equipped with antimicrobial pump tubing. The pump head may be driven with a direct current electrical motor, which in turn is controlled by a power amplifier and the control system 99. Primarily, the pump is operable to draw water from the water tank 20, through the water filter 40, along the UV light source 50, and to deposit such water in the humidification chamber 90 for atomization purposes.

In certain embodiments, the pump's operation can be reversible to move water in both the forward and backward directions. For example, the forward pump action may be used to supply the humidification chamber 90 with water and the backward direction may be used to drain water from the humidification chamber 90 system back into the water tank 20.

As will be appreciated from FIGS. 9A-11 , the exemplary humidification chamber 90 is located just above/downstream from the motorized fan 70, very near the top of the housing 10, at the exit of the humidifier 100, so there is very little distance between the piezos and the terminal end of the housing where water vapor passing through the housing can accumulate or promote pathogen growth.

In accordance with the present invention, the humidification chamber 90 may have any suitable structure. In the exemplary embodiment of the present invention, the humidification chamber 90 has an upper vent 91 and further includes at least one ultrasonic piezo disk 92 having a watertight cap disk 92A and mounted on top a wick carrier disk 94 that provides a plurality of watered cylindrical wicks 93. The wick carrier disk 94 is sized to enable the watered cylindrical wicks 93 to be partially submerged into a dedicated water supply reservoir 96 that is contained within the wick carrier disk 94, as best shown in FIG. 10 . Each piezo disk 92 has electrical connections to a power amplifier housing in the upper housing 18, which generates voltage waveform at its resonant frequency to excite mechanical vibration, extracting water drops from the wick surface layer into the surrounding air. The vibration of each piezo disk 92 can be controlled (by the control system 99) independently depending on the required humidification rate. The extracted water drops vaporize depending on the ambient temperature and vapor pressure, water drop diameter, induced airflow from the fan, and other trace gases present in the air.

The water supply line for the wicks 93 can be designed as a small buffering reservoir 96 that is supplied with the pump outflow. The reservoir 96 may include a spillway draining to overflow tubing 98 passing from the spillway back to the inlet port 26 and associated fitting of the water tank lid 24. In certain embodiments, the humidification chamber 90 is further provided with an overflow valve that cycles excess clean water back to the water tank 20 to prevent leakage from the top side. A more detailed explanation and description of an exemplary piezo disk and wick carrier disk assembly is provided in a copending application Ser. No. ______ filed by the same Applicant of even date herewith, entitled “Humidifier With Improved Mist Generation,” the disclosure of which is incorporated by reference.

It will be appreciated that the water filter 40, UV light source 50 and pump 60 can be organized in any order, but to maximize the filtration performance, particular pump characteristics, water filter structure and UV light source power should be considered, and parameters should be coordinated to provide the desired efficacy. Continuous or periodic water flow through the water filter 40 and past the UV light source 50 promotes proper water sterilization.

FIG. 13 is a graph illustrating the relationship between relative humidity and air quality index for water containing dissolved solids. More particularly, FIG. 13 shows the observed increase in a particulate matter concentration in room air during ultrasonic vaporization of non-zero TDS water, where ΔAQI is the increase in air quality index and ΔRH is the increase in relative humidity. In accordance with the present invention, an exemplary control system 99 (e.g., housed in the upper housing 18) takes into account the impact of the TDS on the room AQI levels. The theoretical relationship between increase in AQI and increase in relative humidity due to vaporization of TDS containing water is depicted in the FIG. 13 . As can be seen if FIG. 13 , if there is an increase in the relative humidity due to vaporizing non-zero TDS water into the room, then AQI is always elevated due to the generated fine particulate matter in the air as a side effect of the vaporization of water containing TDS. If the TDS of the water is close to zero, then the effect on room AQI due to humidification can be in the reversed. The generated water droplets may help bonding the dispersed particulate material in the air, hence, increasing their aerodynamic diameter. As a result, bonded larger particles may get heavier and tend to drop gravitationally out of the air concentration. Therefore, a water purification system significantly improves humidifier performance.

FIG. 14 is a flow diagram illustrating an exemplary method of operation of an exemplary control system 99 of the exemplary humidifier 100 of FIG. 1 for power management. More particularly, FIG. 14 shows a priming algorithm whereby a water level sensor (e.g., in the nature of a pair of capacitive strips near the water tank 20, and operative to detect a water level just a few mm away, in the water tank 20) is used to detect whether the water filter 40 is still filling with water, while keeping the piezo discs 92 un-powered, and while the pump is operating. FIG. 14 shows the control logic during the priming process, where the volume of water filter 40 has to be filled with water to allow further exploitation of the humidifier. During the process, the piezo disks 92 may be turned off, and the pump may be working at full power. Since the water is being pumped into the water filter 40, the average water tank level will begin to decrease until the entire internal volume of the water filter 40 is filled with water. After the tank level stops decreasing, the priming process is over, and the pump can be turned off or idled for the next operation.

FIG. 15 is a schematic illustrating an exemplary method of operation of an exemplary control system of the humidifier 100 of FIG. 1 during normal humidification operation and shows control system response to various TDS levels detected in the humidification chamber 90. In this exemplary embodiment, a TDS to AQI (air quality index) model determines what will be the expected increase of the room AQI for a particular dose requested by the humidification control system. Here, it is assumed that the humidification algorithm generates a water dose signal required to reach a particular relative humidity level. The dose signal can be dynamically adjusted but it is expected to be low frequency and monotonically decreasing toward the target. The calculated AQI increase from the model is also a dynamic variable which gives the upper bound of the room AQI which can be expected for the requested dose if it were injected and evenly distributed in the current time instant. The room AQI model which accounts for the home ACH, fan ACH, AQI target and outdoor AQI calculate the maximal possible AQI increase rate we can have such that the room AQI is in the safe limits. The increase rate is then fed to the vaporization controller which calculates the upper bounds for the pump rate and for the piezo power, hence, limiting these rates the AQI in the room will be kept within the safe limits for the current TDS concentration in the water. The end effect is that if the water has high TDS, then the vaporization rate will be limited such that the elevated level of AQI due to TDS in the water can be compensated by the current air flow through the device HEPA filter.

The control system 99 can be operatively connected to the system components to provide a suitable signal to the components to control the humidifier device. As will be appreciated by those skilled in the art, the control system may comprise a printed circuit board supporting electrical components implementing suitable logic for carrying out the functionality described herein.

Generally speaking, the control system is composed of hardware level and software level layers. With respect to the software level, the control system may be implemented as an executable entity in a dedicated microcontroller integrated circuit (IC). The control algorithm is commonly performing discrete-event functions. The control software of the humidifier is a composition of various loops of control dedicated to various functions requested by the device.

In addition to the tubing described above, various components of the humidifier 100 can be made using plastic whose exposes surfaces can be embedded with antimicrobial and/or hydrophobic additives. These include the water tank 20, the housing enclosure 10, and the UVC filter 50, for example. The inventive humidifier 100 can reduce the amount of water minerals projected into the air to zero or close to zero and is able to reduce the amount of pathogens projected into the air to near zero. The humidifier 100 can maintain a 2-log or better continuous reduction of microbes from the source water, such as tap water, and the use of antimicrobial and/or hydrophobic additives in and on the exposed equipment surfaces block additional microbial generation. The humidifier 100 can maintain the sterility of any stored water for several days by repeatedly circulating the water through the water filter 40 during periods of use.

While there have been described herein the principles of the invention, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation to the scope of the invention. Accordingly, it is intended by the appended claims, to cover all modifications of the invention which fall within the true spirit and scope of the invention. 

What is claimed is:
 1. A humidifier for humidifying room air, the humidifier comprising: a housing; a water tank in the housing, said water tank defining a reservoir for containing water; a water filter in the housing and configured to capture dissolved solids contained in the water as the water passes through the water filter; an ultraviolet light source configured to kill pathogens contained in the water as they are exposed to the ultraviolet light source; a humidification chamber positioned adjacent an outlet of said housing, said humidification chamber being operable to generate a water mist from the water; a motorized fan operable to create a flow of air moving from the humidification chamber to an exterior of the housing; a pump configured to drive water from said reservoir, through said water filter and through a region exposed to light from the ultraviolet light source, and then into the humidification chamber; and a control system operable to control operation of said ultraviolet light source, said pump, said motorized fan, and the humidification chamber to generate the water mist, and to cause the water mist to become entrained in the flow of air moving from the humidification chamber to the exterior of the housing.
 2. The humidifier of claim 1, wherein the water tank is located at or near a bottom of the housing, the humidification chamber is located at or near a top of the housing, and the water filter is located between the water tank and the pump.
 3. The humidifier of claim 2, wherein the ultraviolet light source is located between the water tank and the pump.
 4. The humidifier of claim 1, further comprising an air filter in the housing, wherein the motorized fan is positioned to draw air through the air filter and to the humidification chamber.
 5. The humidifier of claim 4, wherein the housing comprises a plurality of openings in a wall of the housing and adjacent to the air filter, and the motorized fan is positioned to draw ambient air into the housing through the openings in the wall, through the air filter and to the humidification chamber.
 6. The humidifier of claim 4, wherein the air filter is adjacent to the motorized fan and the fan is positioned between the air filter and the humidification chamber.
 7. The humidifier of claim 1, wherein the humidification chamber comprises at least one piezo disk, and a plurality of wicks below the at least one piezo disk extending into an adjacent water reservoir.
 8. The humidifier of claim 1, wherein the ultraviolet light source comprises a UV-C light source.
 9. The humidifier of claim 1, wherein the water filter comprises an inorganic filtration media having ionic extraction properties.
 10. The humidifier of claim 1, wherein the pump comprises a peristaltic constant displacement pump.
 11. The humidifier of claim 1, wherein the water tank, water filter, ultraviolet light source, pump, and humidification chamber are connected using plastic tubing having at least one surface embedded with antimicrobial and/or hydrophobic additives.
 12. The humidifier of claim 1, wherein the housing is substantially cylindrical.
 13. A humidifier for humidifying room air, the humidifier comprising: a housing; a water tank in the housing, said water tank defining a reservoir for containing water; a water filter in the housing and configured to capture dissolved solids contained in the water as the water passes through the water filter; a first tube leading from the water reservoir to the water filter; an ultraviolet light source configured to kill pathogens contained in the water as they are exposed to the ultraviolet light source; a second tube leading from the water filter to the ultraviolet light source; a humidification chamber positioned adjacent an outlet of said housing, said humidification chamber being operable to generate a water mist from the water; a motorized fan operable to create a flow of air moving from the humidification chamber to an exterior of the housing; a pump configured to drive water from said reservoir, through said water filter and through a region exposed to light from the ultraviolet light source, and then into the humidification chamber; a third tube leading from the ultraviolet light source to the pump; a fourth tube leading from the pump to the humidification chamber; and a control system operable to control operation of said ultraviolet light source, said pump, said motorized fan, and the humidification chamber to generate the water mist, and to cause the water mist to become entrained in the flow of air moving from the humidification chamber to the exterior of the housing.
 14. The humidifier of claim 13, further comprising a fifth tube leading from the humidification chamber back to the reservoir.
 15. The humidifier of claim 13, further comprising an air filter in the housing, wherein the motorized fan is positioned to draw air through the air filter and to the humidification chamber.
 16. The humidifier of claim 13, wherein the first, second, third, and fourth tubes comprise a plastic that has been treated with an antimicrobial additive.
 17. The humidifier of claim 13, wherein the water tank comprises a plastic that has been treated with an antimicrobial additive.
 18. The humidifier of claim 15, wherein the housing comprises a plurality of openings in a wall of the housing and adjacent to the air filter, and the motorized fan is positioned to draw ambient air into the housing through the openings in the wall, through the air filter and to the humidification chamber.
 19. A humidifier for humidifying room air, the humidifier comprising: a housing; a water tank in the housing, said water tank defining a reservoir for containing water; a water filter downstream from the water tank in the housing and configured to capture dissolved solids contained in the water as the water passes through the water filter; an ultraviolet light source downstream from the water filter configured to kill pathogens contained in the water as they are exposed to the ultraviolet light source; a humidification chamber downstream from the ultraviolet light source positioned adjacent an outlet of the housing, said humidification chamber being operable to generate a water mist from the water; a motorized fan operable to create a flow of air moving from the humidification chamber to an exterior of the housing; a pump downstream from the water filter and upstream from the humidification chamber configured to drive water from said reservoir, through said water filter and through a region exposed to light from the ultraviolet light source, and then into the humidification chamber; and a control system operable to control operation of said ultraviolet light source, said pump, said motorized fan, and the humidification chamber to generate the water mist, and to cause the water mist to become entrained in the flow of air moving from the humidification chamber to the exterior of the housing.
 20. The humidifier of claim 19, further comprising an air filter in the housing, wherein the motorized fan is positioned to draw air through the air filter and to the humidification chamber. 